Sugarcane is grown over an area totaling about 20,000,000 hectares in Brazil, India, and other regions, and it is a resource plant used for sugar production and ethanol production. Through the popularization of biofuels in the future, continuous growth of demand for sugarcane is anticipated, and enhanced production thereof is accordingly expected.
With the aim of inexpensive and stable provision of sugarcane plants as starting materials, sugarcane variety improvement and breeding have been actively attempted. To date, sugarcane variety improvement and breeding have been performed via cross-breading (Non-Patent Document 1).
However, sugarcane plants have roots in the tropics, and ear emergence and flowering are impossible in Japan, most of which lies in the “temperate zone.” In addition, due to genomic structural complexity, it has been very difficult to achieve effective variety improvement and breeding.
In the past, cross-breeding was carried out between plant species determined based on experience or intuition, and many progeny plants were extensively evaluated and selected. In order to perform crossing, in general, a process of induction of flower-bud formation, flowering, pollination, promotion of fruition, and seed production is necessary. In the case of sugarcane, this process can be implemented only once a year even in a field that is suitable for growth. Thus, development of a single plant variety was very time consuming.
In addition, it was very difficult to perform crossing as desired in cases in which plant varieties to be subjected to crossing had difficulty of flowering or in cases in which the flowering time of a plant variety was different from that of another plant variety.
Accordingly, there had been a strong demand for development of a method for efficient cross-breeding of sugarcane in the art.
It has been heretofore reported that flower bud formation (ear emergence) had been induced through overexpression of flower-bud-formation-inducing genes, such as FT or OsHd3a genes, in Arabidopsis thaliana or Oryza sativa (Patent Documents 1 to 3; and Non-Patent Documents 2 and 3). In addition, the FT or OsHd3a genes have been found to exert similar effects in many other plant species.
Unfortunately, there has been no report concerning recombinant sugarcanes overexpressing the genes as described above.